Wax-oil separation process



Feb. 23, 1954 c. J. HALAMKA ETAL WAX-OIL SEPARATION PROCESS Patented Feb. 23, y1954 sie* WAX-on. SEPARATION rRoeEss Charles J. Halamka, Richmond, and Lynn R.

La Porte, El Cerrito, Calif., assignors to California Research Corporation, San Francisco, Calif., a corporation of Delaware 4 Claims.

The present invention relates to improvements in processes for separating wax-oil mixtures into valuable lubricating oils and superior wax products. More particularly, the invention pertains to an improved method of solvent dewaxing and deoiling whereby the desired high quality is obtained for both the lubricating oil products and the wax products.

The method of the present invention issuperior to various processes heretofore proposed for separating wax-oil mixtures. Whereas prior methods usually give dewaxed lubricating oils of satisfactory properties, they do not at the same time yield the desired high quality wax products without employingspecial treatments or additives or the like.

It is therefore an object vof this invention to provide an improved process for efficiently sep-- arating wax-oil mixtures into lubricating oils and waxes of high quality.

A particular object of this invention is to provide an improved process for obtainingrelatively low melting point wax of superior characteristics.

A further object of this invention is to recover a greater amount of low melting point oilfree waxes than heretofore recovered in deoiling operations.

Further objects and advantages of my invention will appear from the following description taken in connection with the attached drawing which is a schematic flow diagram ofl a preferred embodiment.

Briefly stated, the present process involves the following steps: A waxy oil is first separated by solvent-dewaxing into dewaxed oil and primary slack wax. The primary slack wax is then fractionated into primary wax distillates of relatively narrow boiling point ranges including a lowboiling fraction which .on deoiling yields waxes having an average melting point in the range of 127-140 F. AMP (i. e., American Melting Point, as dened in ASTM 1387-42). Preferably, these low-boiling distillate cuts are such that the waxes produced on deoiling can be classified as y125/127, 12S/130, 133/135 AMP grades or cornbinations of two of these such as an 125/130 AMP grade. Likewise produced is a higherboiling primary slack wax distillate, which yields by deoiling, a wax having an AMP of 13B-160 F., preferably having an AMP at least F. higher than the wax resulting from normal solvent deoiling of the low-boiling `primary slack wax distillate selected. Thereafter a primary wax distillate of such higher average boiling point is solvent-deoiled to product a wax product Application January 6, 1951, Serial No. 204,806

and a foots oil. While the fraction boiling next above said selected low-boiling fraction is preferred, other higher primary wax distillates up to those which, on deoiling, give waxes with a maximum of about 160 F. AMP can be used. The foots oil so obtained is then solvent-dewaxed to obtain a high quality lubricating oil component and a secondary slack wax. At least a portion of the secondary slack wax is then combined with the selected low-boiling primary wax distillate in a ratio of 20-35 volumes of secondary slack wax to -65 volumes of said primary wax distillate. This wax mixture is then subjected to solvent-deoiling to produce a wax product of the desired high quality.

For purposes of this invention, a waxy oil is defined as an oil derived from crude petroleum containing parafnic compounds which are normally solid at room temperature. The percentage of such petroleum paraffin wax may vary from 1 to 25% in a virgin crude oil, or from 2 to 50% in topped crude oil or distillate fractions or in waxy raninates obtained from solvent treating or deasphalting distillate fractions or residua. The slack waxes obtained by dewaxing usually contain about 1060% of a zero F. pour point oil, although the .oil content can be as low as 2,3%. The wax in the low-boiling distillates of primary slack wax is substantially all (i. e., more than about normal or straight chain paranic compounds. In the secondary slack waxes as obtained by solvent-dewaxing a foots oil resulting from deoiling a primary slack wax distillate, the wax is predominately (i. e., more than about 75%) non-straight chain parailinic compounds. Both of these petroleum paraffin waxes are to be distinguished from petroleum microcrystalline or amorphous wax; for example, the paran waxes, which are obtained fromdistillates, have low melting points and low tensile strengths, whereas microcrystalline waxes which are obtained from residuum are relatively high melting and have high tensile strengths. Thus, although tnelow melting point paraffin wax products of the present invention have surprisingly good tensile strength, they are not the same as the products obtained by incorporating a high tensile strength petrolatum (i. e., slack microcrystalline wax) into paraiiin wax, as described in Adams Patent 2,127,668.

In some instances it is most advantageous to distill the secondary slack wax to produce a lower boiling fraction and a higher boiling fraction in which case the higher boiling fraction, comprising about ,B0-80%, preferably ,3D-,60%,

oiling temperature, i. e., about 35-55 F., the oilfree wax is separated from the foots oil in a suitable manner; such as by means of a continuous filter. The wax product contains less than 1%, preferably less than 0.5%, oil.

For fractionating the primary slack wax into relatively narrow boiling distillates, it is preferable to employ a fractionating column operating under a low vacuum sufficient to avoid appreciable cracking of the paraffin wax. steam may be introduced into the column to assist the distillation. While the fractions are separated ordinarily on the basis of the average melting point of the waxes produced by deoiling the distillates, it is generally desirable to obtain at least three fractions with average boiling points (atmospheric pressure basis) of about 800"` F., 900 F. and 1050 F., which can be designated as cuts No. 1, No. 2 and No. 3. Cut No.-

1 on deoiling yields a wax having an AMP of about 13S-138 F., and deoiling of No. 1 and No. 2 cuts together yields a wax with an AMP of 14S-150 F.

While for the purpose of carrying out the process of the present invention, separate facilities can be provided for dewaxing and topping or fractionating the foots oil, these facilities can be used intermittently for different feed stocks. Likewise, where in the hereinbelow detailed description one device for chilling the solvent-waxoil mixtures is shown or referred to, the operation can be carried out in several stages.

Since the present invention is especially applicable to the production of a superior wax product melting at 125-130 F. AMP, which product is known as 125/130 grade wax, the process will be described in relation thereto. Referring to the drawing, the waxy oil in feed tank I can be, and preferably is, a solvent-refined lubricating oil stock such as a long residuum (Z-30% from crude) from a California waxy crude (which is classifiable as intermediate by the Bureau of Mines Gravity Classification described by Love & Garton in Bureau of Mines Report of Investigations No. 3279, 1935). The waxy oil is taken from the feed tank I through valved line 2 by means of pump 3 and admixed with dewaxing solvent introduced through line 4. The solventn waxy oil mixture passes through heater 5 which is maintained at a temperature sufliciently high to insure complete solution of the waxy oil in the solvent. Thereafter the mixture is introduced into a chiller 6 for chilling the solvent- Wax-oil mixture to the dewaxing temperature such as about 10 F. The chilled mixture is introduced into filter 1 wherein lubricating oil of low pour point is separated from the waxy material. The ltrate is taken from the iilter by means of pump 8 via line 9 and introduced into a solvent recovery system I0 for separation of the solvent from the dewaxed oil which passes to storage through line II and pump I2. The wax cake produced in the filter is taken by pump I3 through line I4 to solvent recovery system I5 in which the dewaxing solvent is removed via line IE. The solvent-free waxy material passes via line I1 and pump I8, open valve I9 and line into primary slack wax storage tank 2|. During this operation, valve 22 in line 20 remains closed.

The primary slack wax is taken from storage tank 2| by means of pump 23 and passed through line '24, open valve 25 and a suitable heater, such as fired heater 25, into vacuum fractionating column 21. Preferably, steam is introduced through If desired,-

i through line 42.

line 28 into the lower portion of fractionating column 21 to assist the distillation. A sufiiciently low pressure is maintained in column 21 by means of a vacuum system (not shown) connected to the column through line 29 to permit the distillation to proceed without appreciable cracking of the waxy material. In the fractionating column 21 the primary slack wax is separated into the desired number of relatively narrow boiling primary slack wax distillates.

As indicated in the drawing, three distillate cuts can .be taken and passed from the column 21 via lines 3G, 3l and 32 to the respective distillate storage tanks 33, 34 and 35. Line 35 is provided for passing the primary slack wax bottoms to storage tank 31.

In one preferred embodiment of the present invention, an admixture of No. 1 and No. 2 primary slack wax distillates are taken from their respective storage tanks 34 and 35 via valved lines t3 and 3e and header 40 by means of pump 4I, mixing with deoiling solvent introduced through line 42. The resultant solvent primary slack wax distillates are passed first through heater 43 f and chiller 44 and thence into deoiling filter 45.

The wax cake so obtained in filter 45 is removed through line t3 by means of pump 64 in the solvent recovery system 65 from which solvent passes via line tit and by-product wax is discharged through line 51. From the deoiling filter 45'is taken a filtrate comprising solvent and foots oil which passes via line 46 and pump 41 into solvent recovery system 48. The deoiling solvent which is thus recovered may be recycled conducted vialine 49 and pump 5t to foots oil storage tank 5I.

Foots oil is then treated in the solvent dewaxing system to obtain a secondary slack wax and an oil of low pour point. For this purpose the foots oil passes from storage tank 5l via valved line 52, and the eiiiuent of pump 3 is admixed with dewaxing solvent introduced through line 4, the solvent foots oil mixture passing through heater f- 5, chiller 5 and into iilter 1. The secondary slack wax, i. e., the wax so obtained in the filter 1,

passes through line I4, solvent recovery system l5, line I1, pump i8, line 2li and open valvel via line 5G and open valve 53 (valve 51 beingl closed) and through line 59 into secondary slack wax storage tank 60. When the secondary slack wax is fractionated, the desired distillate out or cuts issuing from the fraotiohating column 21 maybe introduced into secondary slack wax storagegtank 60 through suitable conduit lines not shown.

Thereafter the admixture of the selected lowboiling primary slack wax distillate, such as cut No. 1 from storage tank 33 and secondary slack wax from storage tank 30 are passed through the respective valved lines 61 and 52 into header 40, from which pump 4I takes suction to pass the admixture together with deoiling solvent introduced from line 42 through heater 43, chiller 44 and into filter 45. From the filter is obtained as filtrate a secondary foots oil which, after removal of the deoiling solvent in solvent recovery system 48, may be discarded or returned The solvent-free foots oil isv resulting from deoiling the admixture of second- A ary slack wax and low boiling primary Wax distillate is subjected to solvent-dewaxing to produce a third 10W pour point oil and a third slack Wax, and 5 to 15 volumes of said third slack Wax are combined with 20 to 35 Volumes of said secondary slack wax and '75 to 50 volumes of said low boiling primary, slack wax distillate to form an admixture for subsequent solvent-deoiling.

`CHARLES J. HALAMKA. LYNN R. LA PORTE.

References Cited in the 111e of this patent UNITED STATES PATENTS Number Name Date Henderson et al. Dec. 5, 1933 Winning Oct. 1, 1935 Coster Dec. 14, 1937 Adams et al. Aug. 23, 1938 Adams et al Oct. 31, 1944 Bowman et al. Apr. 19, 1949 Ridenour Sept. 23, 1952 

1. THE PROCESS OF SEGREGATING A WAXY LUBRICATING OIL STOCK INTO DEWAXED LUBRICATING OIL COMPONENTS OF LOW POUR POINT AND IMPROVED OIL-FREE WAXES COMPRISING THE STEPS OF SOLVENT DEWAXING SAID WAXY OIL STOCK TO PRODUCE A SUBSTANTIALY WAX-FREE OIL AND A PRIMARY SLACK WAX, FRACTIONATING SAID PRIMARY SLACK WAX INTO A PLURALITY OF RELATIVELY NARROW-BOILING PRIMARY WAX DISTILATES INCLUDING A LOW BOILING DISTILATE WHICH ON DEOILING YIELDS A WAX WITH AN AVERAGE MELTING POINT IN THE RANGE OF 125-140* F. AMP, SOLVENT-DEOILING A PRIMARY WAX DISTILLATE OF INTERMEDIATE BOILING RANGE TO PRODUCE A SUBSTANTIALLY OIL-FREE WAX AND A FOOTS OIL, SOLVENT-DEWAXING SAID FOOTS OIL FROM THE INTERMEDIATE WAX DISTILLATE TO PRODUCE A SECONDARY DEWAXED LUBRICATING OIL COMPONENT AND A SECNDARY SLACK WAX, COMBINING AT LEAST A SUBSTANTIAL PORTION OF SAID SECONDARY SLACK WAX WITH SAID LOW BOILING PRIMARY WAX DISTILLATE IN A RATIO OF 20 TO 35 VOLUMES OF SAID SECONDARY SLACK WAX TO 80 TO 65 VOLUMES OF SAID PRIMARY WAX DISTILLATE, AND SOLVENT-DEOILING SAID MIXTURE OF SECONDARY SLACK WAX AND PRIMARY WAX DISTILLATE TO PRODUCE A LOW MELTING WAX OF SUPERIOR PROPERTIES. 